Re: new submission: AX_CONFIG_PREFIXED_HEADER

[Guido Draheim]

Matto Marjanovic wrote:
> Hiya,
>
> Appended is my submission for a new pair of macros:
>
>     AX_CONFIG_PREFIXED_HEADER(OUTPUT, PREFIX, INPUT)
>     AX_PREFIXED_DEFINE(PREFIX, SYMBOL)
>
>  for release under the "GPLv2 with Autoconf exception" license.
>
> These were inspired by the AX_PREFIX_CONFIG_H macro to solve the
>  same basic problem:  create an installable version of the generated 
>  "config.h" header by prefixing the defined symbols with a PREFIX.
>
> However, instead of copying/prefixing the *entire* input header file,
>  this new pair of macros allows the developer to select exactly which
>  symbols she needs in the installable header file.  AX_PREFIXED_DEFINE
>  is used to schedule a SYMBOL (which should already have a corresponding
>  AC_DEFINE) for prefixing with PREFIX.  AX_CONFIG_PREFIXED_HEADER
>  specifies that the OUTPUT header is generated from the INPUT header
>  using all the symbols scheduled under PREFIX.
>
> It's nice because it creates an installable config header with only
>  the symbols one absolutely needs (and none of the extraneous cruft
>  which may be broken anyhow).
>
> The macros currently have no defaults for the parameters; each parameter
>  is required.  I'm happy to take suggestions for how to improve this,
>  or pointers to examples of the right way to do this, or anything else
>  in the macros.  (This is my first autoconf macro, and I must admit I'd
>  like to take a break from pouring over m4 source code for a while.)

Hi Matt,

great idea, and indeed some people were not all too happy with the
prefix_config_h macro to export all symbols which effectivly means to
export some implementation detail to the user. Since you do check all
exported symbols explicitly, I'd like to remind of two things:
(a) there is need for self-defining macros like AC_*_OFF_T and those
     AC_*_SIZE_T which will define off_t/size_t if not already in the system.
     For the prefixed variant we need to define the default if the original
     macro did tell to not be defined (!!) #define my_size_t size_t
     - may be you could invent a companion prefixed_self_define hint.
(b) the PREFIX runs up twice, and uneccessarily. Better leave the PREFIX
    as a secondary optional argument. Moreover it would be nice to have
    a loop-exporter prefix_defines(list of names), to make things easier.

Just hints though, great work for what you call "first ac macro ever"!! :-)))
-- cheers, guido